1. Field of the Invention
This invention relates to novel inhibited aluminum hydroxide viscosifier compositions containing pseudoboehmite which have been treated to inhibit tri-hydrate formation and to retard boehmite crystallization as well as to a method of producing these novel compositions.
2. Description of the Previously Published Art
Water-based, clay-free drilling fluids for use in drilling bore holes into subterranean formations are disclosed in U.S. Pat. No. 4,240,915 to J. Block containing water and an aluminum hydroxide agent. A conventional method to make this aluminum hydroxide agent is to react an alkali metal aluminate (Na.sub.2 O.multidot.Al.sub.2 O.sub.3 .multidot.3H.sub.2 O) with an acid such as hydrochloric acid (HCl) under high speed agitation to obtain AlO(OH) in the pseudoboehmite form. However, when AlO(OH) is prepared under these conditions the products will eventually convert to the undesirable thermodynamically stable tri-hydrate such as bayerite and gibbsite. One way to slow down this conversion to the tri-hydrates is to add high concentrations of salts such as sodium chloride. However, this addition dilutes the product with excess salt and it provides for a corrosive mixture when used with drilling equipment.
3. Objects of the Invention
It is an object of this invention to provide an improved aluminum hydroxide containing viscosifier.
It is a further object of this invention to obtain an aluminum hydroxide viscosifier composition which inhibits undesirable tri-hydrate formation such as gibbsite and/or bayerite and which inhibits boehmite crystallization so as to maintain desirable rheological properties.
It is a further object to produce an inhibited aluminum hydroxide viscosifier which is essentially tri-hydrate free by adding an inhibiting material directly to the reactants used in making the aluminum hydroxide viscosifier.
These and further objects will become apparent as the description of the invention proceeds.